We seek the role of the isozyme carbonic anhydrase B, the second most abundant protein in red cells, in human physiology; the anion fluxes of red cells and the transport of iodide from blood to thyroid gland will be studied in this connection. The relationship between the Bohr effect and carbonic anhydrase will be studied, with respect to oxygen delivery in vivo. The role of carbonic anhydrase in the progestational uterus will be investigated, with particular attention to the electrolyte milieu at sites of implantation. We plan work on a new histochemical method for carbonic anhydrase, which should give a more precise intracellular localization, and should be more specific, than the presently used technique which utilizes cobalt. This will be used alongside of the autoradiographic method using tritiated acetazolamide. Work will continue on the kinetics of the carbonic anhydrase reaction, with particular attention to thermodynamics and to the mechanisms of inhibition by sulfonamides.